Fixed freeboard spar buoy

ABSTRACT

There is described an instrumentation buoy having an elongated vertical spar, the upper end of which has a collar to which is tied by a group of slack flexible lines, an annular float which surrounds the upper end of the spar. The flexible attachment between the float and the spar isolates pitch and roll motions of the float from the spar while providing coupling to vertical heave.

United States Patent 1191- Lebovits et al.

[ 1 FIXED FREEBOARD SPAR BUOY [75] lnventors: Morris Lebovits; James C. Schaff,

both of San Diego, Calif. [73] Assignee: Global Marine Inc., Los Angeles,

Calif.

[22] Filed: Mar. 8, 1973 [2]] Appl. No.: 339,414

[52] US. Cl 9/8 R [51] Int. Cl. B63b 21/52 [58] Field of Search 9/8 R, 8 P, 8.3 R, 8.3 E

[56] References Cited UNITED STATES PATENTS 1,510,595 10/1924 Hodgson 9/8 R 2,310,017 2/1943 Canon et al 9/8 R 1451 Aug. 13, 1974 3,405,558 10/1968 Koot 9/8 R 3,671,988 6/1972 Newman 9/8 R 3,760,441 9/1973 Handelman 9/8 R Primary ExaminerAlbert J Makay Assistant Examiner--Donald W. Underwood Attorney, Agent, or Firm-Christie, Parker, & Hale 5 7] ABSTRACT There is described an instrumentation buoy having an elongated vertical spar, the upper end of which has a collar to which is tied by a group of slack flexible lines, an annular float which surrounds the upper end of the spar. The flexible attachment between the float and the spar isolates pitch and roll motions of the float from the spar while providing coupling to vertical heave.

4 Claims, 2 Drawing Figures FIXED FREEBOARD SPAR BUOY FIELD OF THE INVENTION This invention relates to marine buoys, and more particularly to a spar buoy having a fixed freeboard.

BACKGROUND OF THE INVENTION With increased study of the oceans and their resources, there is developed an expanded need for deployment of instruments for monitoring environmental conditions over the oceans surface. The use of long spar buoys to provide an oceanographic instrument platform has heretofore been proposed because of its ability to remain relatively motionless under adverse sea conditions of wind, waves, and currents. The spar buoy is not, because of its small cross-sectional area at the surface, subject to heaving due to the rise and fall of the surface with wave action. While this vertical stability may be desirable in some applications, it is preferred in some circumstances that the instrument package remain substantially a fixed distance above the water. Also, the waves have a tendency to wash over the top of a spar buoy or instrument package supported thereon because the spar buoy does not ride up with the cresting of the wave. Also, because of their relatively long length, on the order of 100 feet, spar buoys are not suitable for use in shallow water. On the other hand, conventional floating buoys tend to rock and pitch violently in heavy seas, lacking the stability of the long spar buoy.

SUMMARY OF THE INVENTION The present invention is directed to an improved buoy which provides the pitch and roll stability of the spar buoy with the vertical or heave response characteristics of a surface floating buoy. This is accom plished in brief, by providing a relatively short spar which normally is designed with a slightly negative buoyancy factor. The spar is in turn suspended from an annular float through which the spar extends, the spar being connected to the float by a group of slack lines which extend'radially from a collar on the spar outwardly to the inner periphery of the annular float. This flexible attachment isolates or decouples pitch and roll motions of the float from the spar, yet provides close coupling for lifting the spar vertically as the float rises up the crest of a wave, thus keeping the top of the spar at a minimum distance above the water at all times.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the invention reference should be made to the accompanying drawing, wherein:

The single FIGURE is a perspective view of the buoy.

DETAILED DESCRIPTION Referring to the drawing in detail, the numeral indicates generally a vertical spar made up of a plurality of lengths of pipe of telescoping diameters, including the largest diameter pipe section 12 forming the lower part of the spar, a smaller diameter pipe 14 forming a middle part of the spar, a pipe 16 forming an upper part of the spar, and a thin pipe or rod 18 forming a mast at the top of the spar. A platform 20 is secured to the upper end of the mast on which may be mounted a transmitting antenna 22 and various sensing devices,

such as the wind guage 24 for monitoring environmental conditions and transmitting them to remote receiving locations (not shown). To lower the center gravity of the vertical spar, the power supply and other heavy equipment for the instrumentation package may be located in the lower spar 12 as ballast.

An annular float 26 surrounds the spar 10 at a point near the upper end of the spar section 16. The annular float 26, may, for example, be rectangular in shape and constructed of four hollow lengths of pipe welded at the mitered corners to provide a water-tight, air-tight construction. The float 26 is attached to the vertical spar 10 by a collar 28 and a plurality of chains or other flexible lines or cables 30. The lines 30 extend from the collar 28 to the four corners of the rectangular float 26. The lengths of the lines 30 are substantially longer than the radial distance from the center of the vertical spar to the corners of the float, so that the lines may be slack. This arrangement permits relatively free tilting movement of the float 26 relative to the spar 10, yet provides a definite limit on the amount of relative vertical movement between the float 26 and the spar 10.

Under normal operation, the vertical spar 10 is arranged to have a slightly negative buoyancy. Thus with the float 26 riding on the surface of the water, the spar is supported against the downward pull of gravity by the tensioning of the slack lines 30. Thus as the float rides up a crest of a wave, it lifts the spar buoy vertically so as to maintain the instrument platform 22 well above the water surface by lifting the spar buoy upwards through the lines 30. As the float drops back down after the wave crest has passed, the lines 30 go slack, allowing the spar buoy to sink slowly back down.

It will be seen that this arrangement allows the buoy to respond to vertical wave action, while at the same time retaining the pitch and roll stability inherent in the spar buoy. The flexible attachment by the chains isolates and decouples the pitch and roll motions of the float from the vertical spar. The buoyancy of the spar can be matched to various payloads or other requirements by proper selection of the materials, lengths and diameters of the various spar sections making up the buoy. The spar is constructed so that the center of gravity is well below the center of floatation, insuring that the spar is vertically stable. The spar and float can be easily constructed from standard pipe sections assembled on board ship by welding at the time the buoy is to be dropped in the water. The buoy can be anchored to the ocean floor in conventional manner.

What is claimed is:

1. An instrumentation buoy comprising an elongated spar having a center of floatation above the center of gravity so that the spar remains vertical in water, an annular float, the spar extending through the central opening of the float, and means interconnecting the spar and the annular float, said means providing free vertical and angular movement of the spar relative to the float between predetermined limits, the interconnecting means including a plurality of slack flexible lines secured to the spar at only one point along the longitudinal axis of the spar and secured to spaced points around the periphery of the annular float, the slack lines permitting the point of attachment to the spar to move substantially above or below the float.

2. The apparatus of claim 1 wherein the spar has a negative buoyancy.

3. The apparatus of claim I wherein the spar includes a plurality of telescoping sections of hollow pipe, the larger diameter pipe being at the bottom of the spar.

4. Apparatus of claim 1 wherein the slack lines are attached to the spar near the upper end of the spar and above the center of gravity of the spar. 

1. An instrumentation buoy comprising an elongated spar having a center of floatation above the center of gravity so that the spar remains vertical in water, an annular float, the spar extending through the central opening of the float, and means interconnecting the spar and the annular float, said means providing free vertical and angular movement of the spar relative to the float between predetermined limits, the interconnecting means including a plurality of slack flexible lines secured to the spar at only one point along the longitudinal axis of the spar and secured to spaced points around the periphery of the annular float, the slack lines permitting the point of attachment to the spar to move substantially above or below the float.
 2. The apparatus of claim 1 wherein the spar has a negative buoyancy.
 3. The apparatus of claim 1 wherein the spar includes a plurality of telescoping sections of hollow pipe, the larger diameter pipe being at the bottom of the spar.
 4. Apparatus of claim 1 wherein the slack lines are attached to the spar near the upper end of the spar and above the center of gravity of the spar. 